The smoke is coming from wildfires burning north of the border, the National Weather Service-Grand Forks says. Smoke is traveling south from southwest Ontario and will move across the alert area Friday afternoon through 9 a.m. Saturday.

"The smoke arrives this afternoon into early evening from Bemidji to Moorhead, and during the late evening and overnight from Alexandria to Saint Cloud," the NWS says.

"Smoky conditions could last 6-8 hours at any location. Smoke will begin decreasing from north to south with northern portions of the alert area clearing Friday evening and southern portions clearing out Saturday morning."

The smoke is unhealthy, especially for children and older adults, in addition to people with lung disease, asthma, and heart disease. People working or exercising outside should also take caution.